A patient with severe peptic ulcer disease takes misoprostol for cytoprotection. Misoprostol acts as a synthetic analogue of which endogenous eicosanoid to protect the gastric mucosa?

• A Thromboxane A2 (TXA2)
• B Leukotriene B4 (LTB4)
• C Prostacyclin (PGI2)
• D Prostaglandin E1 (PGE1) ✓

Explanation

Misoprostol is a synthetic PGE1 analogue that acts on EP2/EP3 receptors in gastric parietal cells to inhibit adenylyl cyclase (reducing cAMP) and thereby decrease gastric acid secretion; it also stimulates mucus and bicarbonate secretion and maintains mucosal blood flow via vasodilation. PGE1 (and the related PGE2) are the primary endogenous prostaglandins mediating gastric cytoprotection. TXA2 promotes platelet aggregation and vasoconstriction. LTB4 is a potent neutrophil chemoattractant. PGI2 (prostacyclin) is primarily an antithrombotic/vasodilatory prostanoid.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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